Available online at www.sciencedirect.com
ScienceDirect Procedia Engineering 153 (2016) 761 – 765
XXV Polish – Russian – Slovak Seminar “Theoretical Foundation of Civil Engineering”
DEVELOP AN EFFICIENT METHOD FOR IMPROVING HYDROPHYSICAL PROPERTIES OF AERATED CONCRETE USING INDUSTRIAL WASTE Tkach Evgeniyaa,* a
Moscow State University of Civil Engineering (National Research University), 26 Yaroslavskoye Shosse, Moscow, 129337, Russia
Abstract Disposal of industrial waste is an important factor influencing the safety of human life, on sustainable development of the regions and the efficiency of many industries, including construction, housing and communal services. One of the main ways of recycling of industrial waste, given the hierarchical order is the production of building materials, including environmentally friendly aerated concrete products with the given (normalized) building-technical properties. The disadvantages of aerated concrete include high rates of absorption, of moisture absorption, low resistance to frost. The proposed method improve the hydrophysical properties of aerated concrete by the joint application of waterproofing additives and hydrophobic traeger in the form of pellets made from bitumen and fly ash. Modified concrete has reduced by 30% of the value of the residual moisture, water absorption 38...39% and capillary leak – 30...32%. Modified aerated concrete differs from a traditional to a more uniform fine-pored structure. The results of experimental-industrial tests showed that the proposed technical solutions allow to significantly improve the building-technical properties of aerated concrete, providing it with the competitiveness on the market of construction materials. © by Elsevier Ltd.by This is an open © 2016 2016Published The Authors.Published Elsevier Ltd.access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility ofthe organizing committee of the XXV Polish – Russian – Slovak Seminar “Theoretical Peer-review responsibility of the organizing committee of the XXV Polish – Russian – Slovak Seminar “Theoretical Foundation Foundationunder of Civil Engineering. of Civil Engineering”. Keywords: utilization of anthropogenic wastes, organic modifier, hydrophobic traeger, modified aerated concrete, hydro-physical properties, hydrophobicity, hydrophobic adjuncts.
1. Introduction The increase in consumer demand of builders for cellular concrete precast products is connected not only with
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1877-7058 © 2016 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license
(http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the organizing committee of the XXV Polish – Russian – Slovak Seminar “Theoretical Foundation of Civil Engineering”.
doi:10.1016/j.proeng.2016.08.239
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Tkach Evgeniya / Procedia Engineering 153 (2016) 761 – 765
the implementation of a number of activities of resource conservation, particularly energy conservation in the construction and maintenance of residential and public buildings, but also with the quality of this type of wall material. Cellular concrete with its unique physico-technical properties provides sufficient thermal protection and high comfort areas, economic efficiency in the construction and operation of buildings grants. The known disadvantages of concrete include high residual moisture content, water absorption, sorption humidity [1-4]. To improve these indicators allows the use of waterproofing additives, but in practice this is not always implemented [5-6]. The technical capabilities of the known waterproofing additives made on the basis of a direct emulsion of bitumen, distillation residues of synthetic fatty acids (DRSFA), soapstone etc., can be considered exhausted [7]. Increase dosage waterproofing additives can significantly improve the hydrophysical properties of concrete (for example, water absorption is reduced in 3-4 times or more), however, the reduction of concrete strength in this case will be an avalanche [8]. 2. Problem statement The goal of the presented research is to develop an efficient method for the hydrophobization of concrete, does not have a negative influence on its durability. A solution to this problem is the use of hydrophobic organic traeger in the form of pellets normalized granulometric composition [9-11]. The term tragen –was used in the manufacture of waterproofing additives in selling solid form (briquettes, pellets, tablets) [12-15]. As the traeger surface-active substances (surfactants) are finely powdered limestone or fly ash. In this case, the traeger has not only the role of the carrier a surfactant, but is also water absorption mixture of all components of the modifier, providing its formability. To granulated modifiers in the technology of concrete required for the dissolution of granules in the process of preparation of concrete mixtures. To granulated modifiers in the technology of concrete required for the dissolution of granules in the process of preparation of concrete mixtures. In this paper, a granular water-insoluble hydrophobic traeger is considered, which is increasing the concentration of water repellent to at least 10% by weight of the binder. The proposed method improve the hydrophysical properties of aerated concrete by the joint application of waterproofing additives and hydrophobic traeger in the form of granules with a maximum size of 5 mm, made of bitumen and fly ash (also possible to apply quartz sand). Preparation method of hydrophobic traeger consists of the following technological operations: – loading the bitumen in the heated mixer, in which the bitumen is melted; – the combination of fly ash with molten bitumen in a ratio of 1:2; – flow of the mixture of bitumen and fly ash by means of a feeder via the hopper into the extruder; – extrusion of the mixture through the die of the extruder hole diameter 2...3 mm; – receipt with cutter pellets-cylinders, which are served on a plate granulator, where the granules effusions powdered by cement; – feeding the finished powdered granules to the finished goods warehouse. The purpose of the hydrophobic part of the traeger produce in terms of the situation of the construction market, cost and availability of raw materials. Granular compositions the hydrophobic traeger and the general requirements are given in table 1 and 2. As a mineral filler used fly ash with a specific surface of 3500 cm2/g or fine Sands with a fineness modulus of 1.5-2 meeting standard requirements. As the fibrous filler used acrylic polymer and polyamide fibers. Table 1 – Formulations of hydrophobic granular traeger. Components Vat residues of synthetic fatty acids Mineral powder Portland cement Fiber drive Technical lignosulphonates Water
The contents by weight. % 1 composition 2 composition 30 33,2 35 36,5 6 6,5 5 8,6 – –
3 composition 35 40 12 10 – The rest
4 composition 30 30 – – 30
Tkach Evgeniya / Procedia Engineering 153 (2016) 761 – 765
Table 2 – General requirements for granular hydrophobic traeger. Indicators Fraction of granules, mm The strength when compressed in the cylinder, MPa Average bulk density, kg/m3 Water resistance
Norm 3 -5; (5-10) 2,50 -3,50 800 -900 (1000) 0,8-0,9 (1)
Fig. 1. Ɋhotograph of the hydrophobic traeger
Figure 1 shows how the mineral filler agglomerated by bonding together particles of complex adhesive consisting of a surfactant (DRSFA) and hydrated cement. 3. Results and discussion Test results show that the use of hydrophobic traeger on the basis of low-grade bitumen allows to reduce up to 15% of the consumption of mixing water and thus to reduce the moisture content of the concrete up to 28%.The concretes modified with water-repellent additives for bitumen emulsion and hydrophobic traeger, which differ from conventional concretes relatively low rates of moisture absorption, water absorption, thermal conductivity, high resistance to alternating moistening and drying, and frost. Production work on the implementation of research results were held at the company Stroykomplekt (Selyatino, Moscow region). Hydroactivation of cement was performed directly in the shop before preparation of concrete mixture. The duration hydroactive of cement was 1.5 min, which allows to obtain a specific surface area of cement...about 4500 4600 cm2/g. Concrete mixture was prepared on the existing equipment of the plant. The basis of the accepted method of preparation of concrete mixtures and the raw materials was used in the enterprise. It should be noted a number of differences: – for "degreasing" of the aluminum powder of the conventional technology foreclosed sulfonol and applied the bitumen emulsion, which in this case acts as a "degreaser" and the stabilizer to prevent sedimentation of the aluminum powder and the role of water repellent for concrete; – hydroactive cement produced simultaneously with the preparation of a slurry of aluminum; – concrete mixture is prepared in the following sequence: first, in the hydrodynamic mixer filed hydroactivated cement and aluminum powder suspension in bituminous emulsion, then a portion of the ground sand. The resulting mixture was stirred for 2 min, then combined with a hydrophobic traeger and further stirred for 30...60 seconds until smooth. Thus controlled water-solids ratio (W/S ≈ 0,32). Thermal processing was carried out on mode 1,5+7+1,5 h at 0.8 MPa. The basic properties of modified concrete are shown in table 3.
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Tkach Evgeniya / Procedia Engineering 153 (2016) 761 – 765 Table 3. Properties of aerated concrete prefabrication
View of concrete Regular aerated concrete Modified aerated concrete
Average density, kg/m3
The ultimate strength in compression, MPa
Residual moisture, %
Water absorption by weight, %
Capillary leak, %
600
3,54
38
34
28
600
4,00
26
21
19
An important characteristic that reflects the ability of moisture to migrate in the pore space of porous concrete is capillary suction. The test results of the developed aerated concrete on water absorption and capillary leak have shown that the water absorption and capillary suction of modified aerated concrete is reduced almost 2 times. This is not only the hydrophobic properties of the modified aerated concrete, but also formation in the larger part of closed pores and smaller diameter of capillary pores. Fig. 2 shows the microstructure of modified aerated concrete.
Fig. 2. Microstructure of modified aerated concrete
Modified concretes have a uniform porous structure and lower capillary porosity of interporous partitions. Such concretes have high performance properties, provide comfortable conditions inside buildings.
4. Conclusions Analysis of research results shows that the modified concrete in compare with concrete, made according to traditional technology, has higher physical-mechanical and hydrophysical properties. Modified concrete has reduced by 30% of the value of the residual moisture, water absorption on 38...39% and capillary suction on the 30...32%. The proposed technical solution significantly improve building-technical properties of aerated concrete, providing it with the competitiveness on the market of construction materials. References [1] Telichenko V. I., Oreshkin D. V. Material science aspects of geoecological and ecological safety in construction //Ecology of urbanized areas . 2015. No. 2. - p. 31-33. [2] Graphkina M. V., Potapov A. D. Estimation of ecological safety of construction systems such as natural-technogenic complexes (geographic basis)] / / Vestnik MGSU. 2008. - No. 1. –p. 23-28. [3] Knyazeva V. P., Mikulski V. G. Skanavi N.. The ecological approach to the assessment of building materials from industrial wastes // Construction materials, equipment, technologies of XXI century. – 2000. -ʋ – p. 16-18. [4] Oreshkin D. V. Problems of building materials and production of building materials // Building materials. 2010. No. 11. P. 6-8. [5] Zhukov A. D., Chugunkov A.V., Khimich A. O., And Eremenko, A. A., Kopylov N.. A Complex analysis of the aerated concrete technology
Tkach Evgeniya / Procedia Engineering 153 (2016) 761 – 765 // Vestnik MGSU. 2013. No. 7. p. 167-175. [6] Lotov V. A., Mitina N.A. The features of the technological processes of production of aerated concrete // Building materials. 2000. No. 4. p. 21-22. [7] Resin V. I., Sakharov G. P., Strelbitsky V. P. The problem of energy efficiency of buildings and constructions // Industrial and civil construction. 1996. No. 5. p. 2-4. [8] Batrakov V.G., Modified concretes. – : Stroyizdat, 1998. p.– 231. [9] S.W. Muzenski, I. Flores-Vivian, K. Sobolev The development of hydrophobic and superhydrophobiccementitious composites, Proceedings of the 4th International Conference on the Durability of Concrete Structures, ICDCS 2014 (2014). [10] Orlova A. M., Popova M. N. Modern problems of solid waste. – monograph Moscow: MGSU, 2010. – p.-216 . [11] Tkach E. V., Semenov V. S., Tkach S. A., Study of the influence of organic additives on the performance properties of fine-grained concrete // Industrial and civil construction. 2013. No. 9. p. 16-19. [12] Tkach E. V. Comprehensive gidrofobizatsii modification of concrete (monograph). – M.: FGBOU VPO MGSU, 2011. p.-232. [13] Tkach E. V., Semenov V. S., Tkach S. A. Hydrophobized modified high performance concrete with improved physical and technical properties // Concrete and reinforced concrete – glance at future: scientific papers of the III all-Russian (II International) conference on concrete and reinforced concrete (Moscow, 12-16 may 2014): in 7 t. T. 5. p. 113-123. [14] 14.TkachE.V, SemenovV.C., TkachS.A., RozovskayaT.A. Highly effective water-repellent concrete with improved physical and technical properties/ Procedia Engineering 24 th Cep. XXIV R-S-P seminar – Theoretical Foundation of Civil Engineering, TFoCE 2015.– p.763769. [15] Tkach E. V., Semenov V. S. Improvement of hydrophysical properties of aerated concrete with industrial wastes // Scientific review. – 2015. No. 14. – p. 194-196
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